Common Denominator
by Faux Promises
Summary: Trust had never existed between them before, but they certainly were getting closer to it. One-shot fluff/introspect.


**A/N**: I felt like writing a little bit of fluffy stuff. I don't know why, just humor me. Kind of ties in with another fic I did, "Convergence," but they aren't so intertwined that I would slap them together into one.

Disclaimer: Don't own Portal.

"_We're never so vulnerable than when we trust someone - but paradoxically, if we cannot trust, neither can we find love or joy."_ ~Walter Anderson

Sprawling across the page like the foul serpent that it was, the equation had practically begun to laugh at her. The stupid thing was adding insult to injury, mocking someone who was already down. A situation the young woman already suffered through enough…enough to be greatly annoyed at the thought of a bunch of words and numbers defeating her.

With a tired sigh, Chell began scrubbing the eraser across the paper in angry strokes. Back to square one.

An amused laugh filled the room. "…And that makes seven."

Increasingly irritated, she dropped the pencil onto the open textbook in her lap with a _thunk_. "Seven what?"

"Seven failed attempts at that problem. _Obviously_."

The woman propped her arms up behind her head, leaning back in her seat. After having had enough of Aperture's uncomfortable metal floors, one visit she decided to just drag one of the old office chairs into the large central chamber that the supercomputer inhabited. And, true to form, GLaDOS immediately reminded her former test subject that the room was _not_ hers to redecorate—as if she were painting the walls and picking out furniture, Chell thought wryly.

"Didn't you say you were going to be 'very busy' today?" she finally replied, a hint of teasing in her voice. "You certainly have enough time to monitor my progress...or rather, lack thereof."

As expected, the AI withdrew slightly into herself in disgust. "I _am_ very busy, for your information. But in case your brain-damaged memory has failed you, let me just say that I'm quite capable of multi-tasking. Currently running several million processes, in fact."

"Uh-huh." Chell had taken to drumming her pencil idly against the cover of her heavy chemistry textbook. No matter how long they knew each other, GLaDOS was always going to deny taking any interest in her. "Well, if you're done laughing at my expense for now, I think I'll see if eight times is a charm for this one."

Somewhat reluctantly, she started writing out the figures she would be using to determine the answer. Perhaps she had been looking at this same problem for too long…it was always difficult to catch a mistake once the frustration had set in. Then again, with a major exam next week, she supposed she had better be prepared for this level of difficulty.

"You know…as much as I can understand a love for science, I do have to ask why you're in _here_ doing _that _today."

Chell glanced up from her work, a bit taken aback by the AI's uncharacteristically bemused tone. "I _do_ come here every month, same day, don't I? What's not to get?"

"I suppose I should frame the question differently," GLaDOS sighed, over-exaggerating her irritation. "For the first time this year the weather is in mid-eighties, slight breeze, zero percent chance of precipitation. Shouldn't you be frolicking up there like a good little human?"

"Oh, so you've been doing some research on humans then, I take it?" Chell flashed a smile that could only be described as defiant. As usual.

"Please, don't assume humans are that difficult to understand. I could abridge human psychology into a pamphlet."

A genuine laugh escaped the woman. "But doesn't your 'human psychology' think cake is an appropriate motivator for deadly testing?"

There was a brief silence, only broken by an agitated 'hmph' from the computer. "I remember promising you grief counseling, too. Don't unfairly villainize me."

The human had to smile at this. Even as GLaDOS grew reluctantly more fond of her, she still wouldn't give up on being combative and generally unpleasant when she so felt like it. It seemed to amuse her that Chell could hold her own in a verbal battle.

"So, you wanted to know why I'm not enjoying the nice summer weather, hm…" the woman mused, setting her pencil down again. "Mostly because I have a major test on Monday, and this chapter has been kicking my ass for the past two weeks."

"That's because you're careless and don't show your work clearly." The AI eyed her with much scrutiny, though Chell found it distinctly softer than her hate-glares. Her tone turned a bit less harsh, as if she'd caught herself. "…I've told you several times, keeping your work neat is essential on complex problems. Humans are prone to error when they take shortcuts."

Chell gave a short sigh, nodding the slightest bit as she went back to rewriting the problem. She _was_ right, though it did annoy her to admit it. In fact, GLaDOS hadn't hesitated to assert herself over the human in quite a maternal fashion ever since Chell had first returned to see her the previous year. Following the revelation that she was the daughter of Caroline, the AI seemed to be competing with the woman who she shared a body with. Even though she begrudgingly allowed Caroline to remain, GLaDOS seemed determined to assume the role of 'mother' in her own unique way.

Like most of Aperture's AIs, she certainly had an…_eccentric_ personality. From what Chell knew of Caroline's personality, GLaDOS definitely could not have been based on her mother. Perhaps she would never know for sure where the AI's twisted nature came from. There was, however, no denying that she was every bit as feminine as any human could be. The catty insults proved that, in addition to her recent bursts of motherliness. And with _that_ domineering attitude, it was no wonder she had always thought of the slightly-insane computer as an overbearing mother.

Perhaps the most ironic part of it all was that despite all the cruel jabs about Chell being adopted, it seemed GLaDOS had unwittingly adopted her herself.

Punching a few numbers into her calculator, she shook her head. You just never knew what strange twist fate had in store for you. But all of this reminded her of something she hadn't asked in a while. She closed her book for a moment.

"So…how's Caroline been doing?"

The AI looked down at her with some skepticism. Chell had been careful about how she worded it; the word 'mom' seemed to provoke some thinly veiled jealousy on GLaDOS's behalf. She didn't like sharing _anything_, let alone someone she had begun to think of as a daughter.

_My self-appointed mother_, she thought with a smile.

"She's been quiet lately," GLaDOS replied tersely. "Not that I'm complaining about that. But it _is_ unusual…she's been disappearing for longer periods of time now."

Chell frowned. "There's nothing wrong, is there? I don't want her to go into hiding again or anything…"

"No, it's not that." The computer shook her head, her voice heavy with a bittersweet mixture of distaste, surprise, and embarrassment. "Actually...I think she finally trusts me with you."

* * *

><p><strong>AN**: Yeah, the paradox quote _was_ intentional. n_n


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